Drainage Arrangements: The Solutions

Our previous blog (read here) discussed the common mistakes we find with drainage arrangements on site. This blog will revisit those problems and suggest solutions for solving the issues.

Vehicle Wash Arrangements

Vehicle wash areas, regardless of scale, must be serviced by foul drainage, preferably with an interceptor. If this is not the case, consider re-siting the activity or collecting the vehicle wash effluent for removal as a waste. This typically involves blocking drains, washing down and then sucking out the effluent. You will also need to ensure that all effluent flows into the correct drain, or area where you are collecting it so you may need to install curbing to ensure there is no overflow to surface water drains or unmade ground. If these options are not possible, you might need to cease vehicle washing and find an alternative, such as off-site washing.

Floor Wash Effluent

Floor wash effluent must be discharged to the foul drainage system with no effluent escaping to surface water. To achieve this, you may need to change the discharge point or put in an access point to the foul line.

Trade Effluent Licencing

All effluent should be discharged to the foul sewer with the relevant permissions in place. If you already have permission, usually a trade effluent consent, you should review it to make sure the conditions are followed, including making sure that all activities that create effluent are included, that the limits are followed (e.g. limits on discharge quantity, time of discharge or the composition of the effluent) and that any monitoring required is carried out. If the consent does not include everything, for example, it covers vehicle washing, but not floor washing, you should contact your provider to have it amended. If the limits are not followed, this will also need addressing e.g. you may need to introduce monitoring, adjust the activity or introduce controls at discharge points (e.g. removing solids from floor wash effluent). If there is no effluent licence in place, you will need to apply for one with your water company.

Drain Confusion

If unsure of your drainage arrangements, you should consult your drainage plan (read more here) and paint your drains accordingly (red for foul and blue for surface) to clear up any confusion. When checking your drainage plan, you should make sure it is accurate by assessing actual drainage arrangements (are drains where the plan indicates), the date of the drawing and the source e.g. is it planned build or from a survey. If there is no drainage plan, or you think your plan is incorrect, you should have a drainage survey conducted to verify drainage arrangements and have an accurate plan drawn up.

In order to ensure pollution does not enter the environment from your activities, you need to manage them and correct any issues. This includes being aware of your drainage arrangements, ensuring effluent is only discharged to the foul drainage system and having all the correct permissions in place and following the requirements.